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Agroecology May Be A Sustainable Solution to Protecting Groundwater

April 8, 2014

On the eve of our son’s birthday, I was again reminded of the large experiment that we have allowed ourselves to be in (see previous posts). New research apparently demonstrates that our # 1 herbicide is actually bioaccumulating in our bodies (

In this blog, I will discuss the role of agroecology in reducing the need for pesticides and protecting our groundwater.

There is increasing disease pressure in both raspberry and blueberry production over the Abbotsford aquifer that is requiring new and stronger pesticides

There is increasing disease pressure in both raspberry and blueberry production over a vulnerable aquifer that supplies drinking water to our communities that is requiring new and stronger pesticides

Other professionals have made agricultural management suggestions regarding protection of our groundwater in the aquifer. Ageson ( suggested that Abbotsford could pay farmers to plant benign crops such as pasture. Golder Associates ( suggested financial incentives to implement groundwater related activities such as nutrient management and irrigation plans. In 2006, I suggested that our community could provide incentives for composting to divert excess manure and nutrients to protect our ground and surface waters.

Implementing agroecological principles may provide a sustainable solution to managing our soils above vulnerable aquifers. The two main tenants of agroecology are adding organic matter to our soils to increase soil health, and implementing biodiversity to increase natural pest resistance.

Agroecological systems are based on the following principles:

1. reduce the use of environmentally damaging, manufactured, costly or scarce inputs, increase the use of natural, local inputs, and enhance biological interactions to promote ecological processes and services. For example, to replace the use of synthetic nitrogen fertilizers; or the use of in-field biodiversity and biological controls to manage pests, diseasesand weeds and to reduce, or where possible eliminate, the use of chemical pesticides.

2. Minimize the quantites of toxic or polluting substances released to the environment.

3.  Manage nutrients more efficiently by recycling biomass and regularly adding crop residues, animal manures and composts, to enhance organic matter accumulation in soils and to balance and optimize the nutrient cycle

4. Increase the soil cover, for example through cover crops and green manures and reduce the amount of tillage, if possible to zero, to minimize soil erosion and the loss of water/moisture and nutrients. These practices, together with water harvesting, aim to use water more efficiently.

5. Promote soil biological activity to maintain and enhance soil fertility.

6. Maintain high species and genetic diversity in time and space and a complex agro-ecosystem structure, in order to provide a range of important ecological services and increase the agro-ecosystem’s resistance and resilience to changes.

Many international organizations are embracing agroecology as the most likely strategy to meet future world food requirements. In 2010, the United Nations General Assembly suggested that agriculture “should be fundamentally redirected towards modes of production that are more environmentally sustainable and socially just”, and defined agroecology as follows:

“Agroecology is both a science and a set of practices. It was created by the convergence of two scientific disciplines: agronomy and ecology. As a science, agroecology is the “application of ecological science to the study, design and management of sustainable agroecosystems.” As a set of agricultural practices, agroecology seeks ways to enhance agricultural systems by mimicking natural processes, thus creating beneficial biological interactions and synergies among the components of the agroecosystem. It provides the most favourable soil conditions for plant growth, particularly by managing organic matter and by raising soil biotic activity. The core principles of agroecology include recycling nutrients and energy on the farm, rather than introducing external inputs; integrating crops and livestock; diversifying species and genetic resources in agroecosystems over time and space; and focusing on interactions and productivity across  the agricultural system, rather than focusing on individual species. Agroecology is highly knowledge-intensive, based on techniques that are not delivered top-down but developed on the basis of farmers’ knowledge and experimentation.”


We need to understand what agroecology is. Its more than simply organic farming. The quotations further in this blog come from Miguel Altieri and Clara Nicholls (

The need for pesticides and chemicals are reduced when we take care of our soil:

“The ability of a crop plant to resist or tolerate pests is tied to optimal physical, chemical and biological properties of soils. Adequate moisture, good soil tilth, moderate pH, right amounts of organic matter and nutrients, and a diverse and active community of soil organisms all contribute to plant health… There are positive interactions between soils and pests that once identified can provide guidelines for optimizing total agroecosystem function.”

The need for pesticides and chemicals are reduced when we increase our biological diversity:

“It is widely believed that agroecosystem diversity is associated with long term stability of included populations, presumably because a variety of parasites, predators, and competitors is always available to suppress population growth of potential pest species. Dispersal of food plants among other nonhost plants may make migration, host, and mate location, and consequently exponential growth of phytophages or pathogens, more difficult. Plant diversification of agroecosystems can result in increased environmental opportunities for natural enemies and, consequently, improved biological pest control.

Research has shown that by adding plant diversity to existing annual monocultures, it is possible to exert changes in habitat diversity which in turn favor natural enemy abundance and effectiveness. This information can be used to design mixed cropping systems that enhance predator and parasitoid diversity and abundance, thus resulting in lower pest loads than in monocultures.

The enemies hypothesis attributes lower pest abundance in intercropped or more diverse systems to a higher density of predators and parasitoids“

Agroecology is about reducing the need for pesticides through building up natural “immunity” in the soil and the plants, but does not suggest that pesticides should be completely eliminated in all situations:

“Large scale commercial agriculture involving crops that have a major complex of pests are initially likely to require the integration of chemical and cultural pest control methods along with the use of natural enemies. In such cases the conversion to a production system totally dependent on biological control will require a stepwise process of agroecological conversion including the efficient use of pesticides (IPM), input substitution (the replacement of insecticides for botanical or microbial insecticides) ending with the re-design of a diversified farming system which provides the environmental conditions for natural enemies, thus allowing the agroecosystem to sponsor its own natural protection against pests.

Emphasis is on preventing pest problems by enhancing the «immunity» of the agroecosystem and on integrating pest management activities with other farming practices that maintain soil productivity and crop health, while ensuring food security and economic viability.”

Agroecology recognizes that there is increased disease pressure as we intensify our agricultural production. Increased disease pressure results from the following:

” 1. decreased landscape diversity

2. decreased on-farm plant diversity

3. pesticide induced insect outbreaks

4. fertilizer induced insect outbreaks

5. weather induced insect pest outbreaks

6. changes induced by plant breeding

7. transgenic crops and increased risks of insect outbreaks

Agroecology encourages practices that enhance the greatest abundance and diversity of above and below-ground organisms. While these epigeal and aerial components have usually been considered in isolation from one another, they are dependent upon each other. Producers provide the organic carbon sources that drive the decomposer activity, which is in turn responsible for mineralizing nutrients required for maintaining growth of the producers. On the other hand mutualists, herbivores, pathogens, predators and parasites affect producer-decomposer interactions both by directing changes in the flow of energy and resources or by imposing selective forces.”

Agroecology is not a simple formula. It involves research and experimentation to discover management techniques and companion plantings that provide high yields with less pesticide inputs.

“In agroecology, a need for more categorical research on the use of crop diversification, recommending that more attention should be devoted to:

1. defining ways to suppress pest through diversity without significant yield reductions;

2. determining how mixed cropping systems impact the population dynamics and searching behaviors of natural enemies;

3. discovering methods to make mixed plantings more economically feasible and compatible with conventional farm operations;

4. determining how mixed cropping systems can be effectively combined with other pest control tactics.”

It would be great to be able to use our experiences, our creativity and our knowlege to model healthy ecosystem management while producing safe and nutritious foods, as well as providing incomes to our farming community.

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